It depends upon the flexibility of the recipient. If you're buying from a retailer, using a debit/credit card is probably easiest and cheapest. Alternatively, if the vendor accepts PayPal, that will be fairly cheap.
However, if you're sending money to a friend (or to someone else who's prepared to go along with your method of payment), Ikobo offers a very useful service. Basically, you pay the money to Ikobo and they send the recipient a prepaid Visa card, which can be used at any ATM which accepts Visa (which is probably almost every ATM in the world). I've used Ikobo on loads of occasions, without any problems, and I recommend their service:
http://tinyurl.com/ikobo
Unfortunately, if the recipient is only prepared to accept the (approximate) international equivalent of a cheque or postal order, you're stuck with services such as Moneygram or Western Union. (If you're moving very large sums of money, you're bank might be able to offer cheaper options but they're not normally of any use for relatively small amounts).
Chris